[systemd-devel] "Correct" way to obtain DHCP lease info?

[Mantas Mikulėnas]

On Thu, Apr 22, 2021 at 6:17 PM Bruce A. Johnson <
bjohnson at blueridgenetworks.com> wrote:

> Silvio, thanks for the suggestion. I'm not concerned with keeping the
> lease forever; the system actually experiences a topology change as it's
> switched from one network to another, and I can catch that from the DBus
> events that occur. The problem we're trying to solve is to contact some
> address that we're sure exists on the network, without knowing anything
> about that network. The default gateway was an obvious choice, but someone
> wants to cover the case of there being a private LAN with no gateway. The
> only other choice I could see is the DHCP server that issues the lease.
>
Hmm, don't you also have the case of there being a private LAN with no
gateway and no DHCP? Or possibly the case of a DHCP relay. And since you
don't know anything about the network, you also don't know whether the
address will respond to your communication attempts (other than ARP) -- it
might be pingable but it might be not.

I'm curious about what brought this problem into existence in the first
place. Why *is* it necessary to contact a random address within the
network? (If it's to check that the physical interface is working, then
just the fact that you somehow acquired a lease would be enough. no?)

-- 
Mantas Mikulėnas
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